ObjectiveThe defects of the wood component with transverse cracks will cause fracture damage under bending load. It is important to study the law of crack initiation and propagation to predict and evaluate the fracture damage of the timber-containing members.

MethodThis paper was performed on Chinese fir and damage was monitored in-situ in real time based on acoustic emission (AE) and digital image technology (DIC) during three-point bending failure of wooden beams with prefabricated transverse cracks. The AE parameter analysis method was used to study the characteristics of AE signals during the crack initiation and propagation of Chinese fir. The strain characteristics of the surface of the wooden beam are also analyzed according to the strain and displacement changes of the crack tip region.

ResultThe results showed that the crack initiation and propagation laws reflected by the AE and DIC measurements during the damage evolution of prefabricated cracks in wood beam specimens were consistent, the digital images of damage evolution from monitoring the crack tip region of wooden beams verify the prediction of AE signals, and AE ring count, energy and amplitude were effective indicators to predict the crack initiation of wooden beams. The strain of the wooden beam surface can effectively observe the evolution of crack initiation and extension.

ConclusionThe results of this study establish the relationship between wood microcrack initiation, propagation behavior and acoustic emission parameters and surface strain, and it successfully construct the evolutionary measurement and evaluation system for in-situ monitoring of cracks in wood components with transverse cracks based on acoustic emission technology and digital image correlation method. The experimental results provide a reference for the further study of the damage mechanism and in-situ monitoring methods for the crack evolution behavior of wood components with transverse cracks.